Linear guide rail and method for working same

ABSTRACT

When working a linear guide rail having one or more raceway grooves  2  on the side surfaces thereof, using rotary dies each including on the circumferential portion thereof a projection-shaped working portion matched in shape to the raceway groove  2,  the raceway grooves  2  are rolled onto a rail blank work W. Since the raceway grooves  2  can be rolled with high accuracy by a single working step, the working time of the raceway grooves as well as the working cost thereof can be reduced.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a linear guide rail and a methodfor working the same and, in particular, to an improvement in working ofone or more raceway grooves of such linear guide rail.

[0003] 2. Description of the Related Art

[0004] Conventionally, a manufacture of a linear guide rail is carriedout through, for example, a step shown in FIGS. 15A to 15F. That is,steel material (work) used as a linear guide rail blank work is drawn tothereby form the outer shape of the linear guide rail as well as theshape of each of raceway grooves 2 (see FIG. 15A).

[0005] Next, the groove bottom portion of the raceway groove 2 of thethus drawn-worked linear guide rail work is cut to thereby form a wireholder groove 3 (or, in some cases, an oil storage groove) for insertionof a wire holder and/or a base surface display line (or a base surfacedisplay groove) 4 for displaying a mounting base surface Wbs (see FIG.15B).

[0006] The above operations are executed as pre-working operations.

[0007] After then, the linear guide rail work is heat treated.

[0008] Next, the linear guide rail is bored to thereby make a mountingbolt hole 5 (see FIG. 15C).

[0009] Then, the upper surface Wa and lower surface Wc of the guide railwork are finish ground (see FIG. 15D).

[0010] Further, the raceway grooves 2 as well as the two side surfacesWbs and Wb of the guide rail work are finish ground (see FIG. 15E). Thegroove grinding operation, as shown in FIG. 15F, is carried out by thesimultaneous grinding operation of the two side surfaces of the guiderail work.

[0011] However, the above-mentioned pre-working operations, that is, thedrawing and cutting operations provides working accuracy and surfaceroughness which are not sufficient as finish accuracy and, therefore, asa finishing step, there is necessary a grinding operation even in thecase of a product which does not require high accuracy, which raises aproblem that it takes long time to work the guide rail and thus theworking cost of the guide rail becomes expensive.

[0012] That is, in the above drawing operation, there can be providedonly the insufficient working accuracy and thus, in the grindingoperation, it is necessary to provide rather large grinding allowance,which results in the longer grinding time. On the other hand, in orderto work a guide rail as accurately as possible in the drawing operation,the number of times of drawing must be increased. In fact, however, eachtime the guide rail work is drawn, it is necessary to execute thefollowing pre- and post-treatments: that is, (1) leader formation (atreatment to narrow the leading portion of the guide rail work so as tobe insertable into a die); (2) annealing; (3) shot peening for removingscales developed in a heat treatment; and, (4) a phosphate filmtreatment. This raises a problem that the working cost of the guide railis expensive and the working accuracy thereof is not so good.

SUMMARY OF THE INVENTION

[0013] The present invention aims at eliminating the drawbacks found inthe above-mentioned conventional linear guide rail and the conventionalmethod for working the same. Accordingly, it is an object of theinvention to provide a linear guide rail and a method for working thesame which, by applying a rolling technique to a linear groove to beformed in the linear guide rail, can reduce the working time and cost ofthe linear guide rail as well as can secure the necessary workingaccuracy of the guide rail.

[0014] In attaining the above object, according to a first aspect of theinvention, there is provided a linear guide rail including one or moreraceway grooves along which rolling bodies roll, wherein the racewaygrooves are respectively rolled.

[0015] According to a second aspect of the invention, in a linear guiderail according to the first aspect of the invention, the surfaceroughness of each of the raceway grooves in the longitudinal directionthereof is in the range of 0.05-0.2 Ra.

[0016] According to a third aspect of the invention, in a linear guiderail according to the first aspect of the invention, the lower surfaceof the linear guide rail is formed in such a dented shape that thewidth-direction two end portions thereof are slightly raised over thewidth-direction central portion thereof.

[0017] According to a fourth aspect of the invention, in a linear guiderail according to the first aspect of the invention, a decarburizedlayer of the surface of a rail blank work is removed before the railblank work is rolled.

[0018] And, according to a fifth aspect of the invention, there isprovided a method for working a linear guide rail having one or moreraceway grooves along which rolling bodies can roll, wherein, using twoor more rotary dies each including a projection-shaped working portionmatched in shape to the raceway groove, the raceway grooves are rolledon a rail blank work.

[0019] According to a sixth aspect of the invention, in a methodaccording to the fifth aspect to the invention, wherein at the same timewhen the raceway grooves are rolled on a rail blank work, the lowersurface of the rail blank work is ground or cut, using two or morerotary dies each including a projection-shaped working portion matchedin shape to the raceway groove.

[0020] According to a seventh aspect of the invention, in a methodaccording to the fifth aspect of the invention, as the need arises, atleast one of chamfering of the corner portions of the linear guide rail,formation of an oil storage groove in the bottom portion of each of theraceway grooves, and formation of a base surface display line is carriedout using the rotary dies simultaneously when the raceway grooves of thelinear guide rail are rolled using the same rotary dies.

[0021] According to an eighth aspect of the invention, in a methodaccording to the fifth aspect of the invention, by rolling the racewaygrooves using rotary dies, the width-direction two end portions of amounting surface of the linear guide rail are projected slightly up fromthe width-direction central portion thereof.

[0022] According to a ninth aspect of the invention, in a methodaccording to the fifth aspect of the invention, there is furtherincluded a sensor for measuring a distance between the working positionsof the rotary dies or a distance between the positions of the portionsadjacent to the working positions, and, while controlling a distancebetween the rotary dies so as to be constant, a distance between theraceway grooves can be maintained stably.

[0023] According to a tenth aspect of the invention, in a methodaccording to the fifth aspect of the invention, there is furtherincluded a sensor for measuring the positions of the raceway groovesjust after the raceway grooves are rolled by the rotary dies, and, thepositions of the raceway grooves are detected by the sensor and, inaccordance with the thus detected values, the positions of the rotarydies are controlled to thereby maintain the inter-raceway groovedistance (the distance between the raceway grooves) stably.

[0024] According to an eleventh aspect of the invention, in a methodaccording to the fifth aspect of the invention, there are included tworotary dies disposed spaced from each other on the side of two racewaygrooves to be formed on one side of the linear guide rail and a rotarydie disposed on the other side of the linear guide rail so as to beasymmetric with respect to the above two rotary dies, whereby the linearguide rail is bent formed using the above rotary dies simultaneouslywhen the raceway grooves are rolled using the same rotary dies, therebybeing able to produce a linear guide rail having a curvature.

[0025] According to a twelfth aspect of the invention, in a methodaccording to the fifth aspect of the invention, the raceway grooves ofthe linear guide rail are previously rolled using the rotary dies andare then heat treated and, after then, the raceway grooves are ground tothereby finish the same with high accuracy.

[0026] As has been described hereinbefore, according to the invention,the raceway grooves of a linear guide rail are rolled in a single stepby using rotary dies each having a projection-shaped working portionmatched in shape to the raceway groove and, therefore, there is requireda smaller working force than a force which is required in theabove-mentioned conventional drawing operation. Also, the rotary dieswear less and thus the lives of the dies can be extended. The tissues ofthe rolling surface are continuous and are thus high in strength.Further, in the case of a product (a linear guide rail) which does notrequire high accuracy, the raceway grooves of such product can be workedwith proper accuracy without cutting or grinding the raceway groovesafter the linear guide rail blank work is drawn as in the conventionalworking method, which can shorten the working time as well as theworking cost of the product (linear guide rail). Use of the rotary diesmakes it easy to guide lubricant onto the working surface of the railblank work.

[0027] Also, in case where chamfering of the corner portions of thepresent linear guide rail, formation of an oil storage groove in thebottom portion of each raceway groove, and formation of a base surfacedisplay line are carried out simultaneously using the same rotary dies,the working efficiency can be enhanced greatly.

[0028] By rolling the raceway grooves using the rotary dies, thewidth-direction two end portions of the mounting surface of the linearguide rail can be projected slightly up from the width-direction centralportion thereof, which makes it possible to stabilize the mounting stateof the linear guide rail more. That is, when a mounting bolt istightened, the mounting contact surface of the rail spreads in the widthdirection thereof and, therefore, even when a lateral load is applied tothe linear guide rail, the linear guide rail can stand firm, therebybeing able to enhance the mounting strength of the linear guide rail.

[0029] Also, in case where the distance between the working positions ofthe rotary dies is measured and the measured value is fed back tothereby automatically control the inter-die distance so as to beconstant, the distance between the raceway grooves of the product can bemaintained more stably, which makes it possible to provide a linearguide rail of high quality.

[0030] And, in case where the rotary dies on the two sides of the linearguide rail are arranged asymmetric with respect to each other, thelinear guide rail can be bent worked by these rotary dies simultaneouslywhen the raceway grooves are rolled using the same rotary dies, therebybeing able to provide a linear guide rail having a curvature.

[0031] Further, according to the invention, the raceway grooves of alinear guide rail are formed with high accuracy by cold rolling themand, therefore, even in case where, as the need arises, the racewaygrooves are heat treated after such cold rolling and, after then, theyare further ground in order to obtain higher accuracy, the grindingallowance of the raceway grooves can be minimized. Accordingly, whencompared with the conventional working method, the grinding time of theraceway grooves can be shortened to thereby reduce the working cost ofthe linear guide rail as well as the degree of bending to be developedby the groove grinding operation can be reduced, so that the racewaygrooves can be finished with high efficiency as well as with highaccuracy.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIGS. 1A and 1B show schematically the main portions of a railraceway groove rolling apparatus according to a first embodiment of theinvention; in particular, FIG. 1A is a side view of the rollingapparatus, and FIG. 1B is a front view thereof;

[0033]FIG. 2A is a graphical representation of the compared results ofhardness between a rail blank work rolled with remaining a decarburizedlayer thereon and a rail blank work rolled after a decarburized layer isremoved therefrom by 0.5 mm;

[0034]FIG. 2B is a view to show a method for removing the decarburizedlayer;

[0035]FIGS. 3A and 3B show schematically the main portions of a railraceway groove rolling apparatus according to a second embodiment of theinvention; in particular, FIG. 3A is a side view of the rollingapparatus, and FIG. 3B is a front view thereof;

[0036]FIG. 4 shows schematically the main portions of a rail racewaygroove rolling apparatus according to a third embodiment of theinvention;

[0037]FIG. 5 is an enlarged section view of the main portions of arotary die for simultaneously working a plurality of portions accordingto a fourth embodiment of the invention;

[0038]FIGS. 6A to 6D are front views of a linear guide rail having adented mounting surface worked according to the invention; inparticular, FIG. 6A shows a linear guide rail having a mounting surfaceof a one-raceway groove type, FIG. 6B shows a linear guide rail having amounting surface of a two-raceway groove type, FIG. 6C shows stresseswhen the present linear guide rail is installed, and FIG. 6D showsstresses produced when a linear guide rail having a conventional flatmounting surface is installed;

[0039]FIG. 7 is a front view of a rail raceway groove rolling apparatusaccording to a fifth embodiment of the invention;

[0040]FIG. 8 is a front view of a rail raceway groove rolling apparatusaccording to a sixth embodiment of the invention;

[0041]FIG. 9 is a front view of a rail raceway groove rolling apparatusaccording to a seventh embodiment of the invention;

[0042]FIG. 10 is a front view of a rail raceway groove rolling apparatusaccording to an eighth embodiment of the invention;

[0043]FIG. 11 is a front view of a rail raceway groove rolling apparatusaccording to a ninth embodiment of the invention;

[0044]FIG. 12 is a front view of a rail raceway groove rolling apparatusaccording to a tenth embodiment of the invention;

[0045]FIG. 13 is a front view of a rail raceway groove rolling apparatusaccording to an eleventh embodiment of the invention; in particular,FIG. 13A shows a case in which one surface is worked, and FIG. 13B showsa case in which three surfaces are worked;

[0046]FIG. 14 shows the relation between the surface roughness ofraceway grooves formed in a linear guide rail and in a slider, which isassembled into a linear guide rail through rolling bodies such as balls,and the variations of the sliding resistance of the slider; and,

[0047]FIGS. 15A to 15F show the steps of working a linear guide railaccording to a conventional working method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] Now, a description will be given below of the preferredembodiments of a linear guide rail and a method for working the sameaccording to the invention with reference to the accompanying drawings.

[0049]FIGS. 1A and 1B show schematically the main portions of a rollingapparatus for rolling one or more raceway grooves onto a linear guiderail according to a first embodiment of the invention: specifically,FIG. 1A is a side view of the main portions of the rolling apparatus;and, FIG. 1B is a front view thereof. Two rotary dies 10 for rolling aredisposed opposed to each other in such a manner that a rail blank work Wused as the blank material of a linear guide rail is interposed betweenthe two rotary dies 10. Each of the rotary dies 10 is a disk-shapedround die in which the direction of its rotary shaft is arranged atright angles with respect to the direction of the axis of the rail blankwork W. The outer peripheral surface (groove working surface) of the die10 is formed so as to have a convex shape which is matched to the grooveshape of each of raceway grooves 2 of a linear guide rail to be rolled,for example, a semi-circular (single R-shaped) convex shape or aGothic-arc convex shape, thereby forming a projection-shaped workingportion T.

[0050] To each rotary die 10, there is additionally connected a drivedevice, that is, a motor 11 for rotating the die 10, and thus the die 10can be driven or rotated by the motor 11 through a belt 12 (that is, thedie 10 is a die of an active type). Also, the rolling apparatus includesa moving and pressing mechanism (not shown) which moves the die 10together with the drive device 11 toward the rail blank work W in such amanner as shown by an arrow mark A in FIG. 1A to thereby press the die10 against the rail blank work W.

[0051] The rotary die 10, which is fed to a pressing position by themoving and pressing mechanism, can be butted against a stopper (notshown) to be thereby positioned there, or can be positioned using aknown positioning and feeding mechanism of an oil pressure NC type or ofa BS drive type which is incorporated in the rolling apparatus.

[0052] Further, the rolling apparatus includes a positioning andsupporting device 13 of an oil pressure type or a fixed type which, inorder to stabilize the position of the rail blank work W in thedirection thereof shown by an arrow mark X in FIG. 1B (that is, adirection shifted by a 90° phase with respect to the mutually opposingdirection of the two dies) in the groove working operation, holds therail blank work W from both sides thereof to thereby press and supportthe same.

[0053] Firstly, a description will be given below of a working step ofworking only the raceway grooves 10 of the linear guide rail, which isexecuted by the illustrated rolling apparatus.

[0054] The rail blank work W is previously annealed so as to havepre-working hardness HRC 20 or lower.

[0055] Also, there exists a thin decarburized layer on the surface ofthe rail blank work W and, therefore, in case where the rail blank workW is rolled as it is, there cannot be obtained sufficient surfacequenched hardness after the rail blank work W is heat treated. In viewof this, before the rail blank work W is rolled, the decarburized layerof the rail blank work W is previously scraped off by an amount of theorder of 0.5 mm. Here, FIG. 2A is a graphical representation of thecompared results of the quenched hardness after heat treatment between arail blank work W which is rolled with remaining the decarburized layerthereon and a rail blank work W rolled with the decarburized layerremoved by 0.5 mm therefrom; and, the horizontal axis of FIG. 2Aexpresses distances from the surface of the rail blank work W whosehardness is to be measured, while the vertical axis thereof expressesquenched hardness at the positions of the respective distances. As canbe seen clearly from FIG. 2A, in the case of the rail blank work W whichis rolled after its decarburized layer is removed by 0.5 mm, thehardness of the surface of the rail blank work W as well as the hardnessof the portion of the rail blank work W adjacent to such surfacerespectively show high values compared with the rail blank work W whichis rolled with the decarburized layer existing thereon. Referring hereto a method for removing the decarburized layer, the decarburized layerexisting in the rail blank work W in such a manner as shown on the leftside of FIG. 2B may be removed into the form of such planes as shown inan upper view on the right side of FIG. 2B, or may be removed into theform of such V-like shapes as shown in a lower view on the right side ofFIG. 2B. In case where the decarburized layer of the rail blank work Wis removed into the form of V shapes, there is obtained an advantagethat a rolling force necessary after removal of the decarburized layercan be reduced. By the way, two semicircles, which are respectivelyshown right and left by broken lines in the right upper view of FIG. 2B,express raceway grooves to be rolled.

[0056] And, the pair of mutually opposing rotary dies 10 are fed totheir pressing positions by the moving and pressing mechanism (notshown) and are positioned there, for example, by making them buttagainst their respective stoppers. In this manner, a distance L betweenthe two rotary dies 10 is previously set so as to correspond to a knowndimension 1 between the two raceway grooves 2, 2 respectively formed onthe two sides of the rail blank work W.

[0057] After then, in a state where the two rotary dies 10 are rotating,the rail blank work W is inserted between the two rotary dies 10, and isheld at its working position accurately by the positioning andsupporting device 13; in this supporting state, the rail blank work W isfed in a direction shown by an arrow mark B in FIG. 1A and is passedthrough between the two rotary dies 10, so that the raceway grooves 2 ofthe linear guide rail are rolling molded on the side surfaces of therail blank work W. To finish the rail blank work W into its final shape,there are available two method: that is, in one method, the rail blankwork W may be finished by passing the rail blank work W through the tworotary dies 10 once; and, in the other method, the rail blank work W maybe finished by passing the rail blank work W through the two rotary dies10 two or more times while changing the distances between the two rotarydies 10. And, the number of times of passing of the rail blank work Wdepends on the kinds of the material of the rail blank work W, theworking accuracy of the grooves, and the shapes of the grooves. Thelongitudinal-direction surface roughness (that is, axis averageroughness) of the raceway grooves 2 worked according to the aboverolling method can be set in the range of 0.05-0.2 Ra. In case where thegroove surface roughness is less than 0.05 Ra, it is difficult to rollthe raceway groove 2. On the other hand, in case where the groovesurface roughness is more than 0.2 Ra, a problem can be easily arisen interms of operation and friction.

[0058] Now, FIG. 14 shows the relation between the surface roughness ofraceway grooves formed in a linear guide rail and in a slider, which isassembled into a linear guide rail through rolling bodies such as balls,and the variations of the sliding resistance of the slider. As can beseen clearly from FIG. 14, in case where the surface roughness Raexceeds 0.2 μm, the varying ratio (the reducing ratio) of the slidingresistance of the slider increases suddenly.

[0059] At any rate, in order to facilitate the working of the racewaygrooves 10, the rolling apparatus, preferably, may include an auxiliarydrive device which is capable of pressing or drawing the rail blank workW to thereby feed the rail blank work W. Such auxiliary drive device mayinclude a pressing device and/or a drawing device.

[0060] Also, the rail blank work W, into which the raceway grooves 10have been rolled, are then machined or bored to thereby form a mountingbolt bore 5.

[0061] Thus, according to the present embodiment, only by a singlerolling step, there can be obtained a linear guide rail having racewaygrooves 10 which have been rolled with proper accuracy. In the case of alinear guide rail which does not require high accuracy, a linear guiderail worked according to the present embodiment can be appliedsufficiently as it is.

[0062] In the case of a linear guide rail which requires extremely highaccuracy, as the need arises, it is also possible to enforce a grindingoperation on a linear guide rail worked according to the presentembodiment.

[0063] Subsequently, the four planes (that is, the upper surface, twoside surfaces, and lower surface of the guide rail) of the rail blankwork W as well as the raceway grooves 2 of the rail blank work W arefinish worked by grinding into high accuracy. This grinding operation,similarly as shown in FIG. 15F, can be carried out by grinding theraceway grooves on the two sides of the rail blank work Wsimultaneously.

[0064] According to the first embodiment of the invention, when comparedwith the conventional linear guide rail working method, there can beobtained the following various operations and effects:

[0065] (1) Since the raceway grooves 2 are rolled using the rotary dies10, not only the present method requires a smaller working force thanthe conventional method which draws a guide rail using a fixed die, butalso the rolling apparatus used in enforcing the present method requiressmaller rigidity and strength than the apparatus used in theconventional method. Further, due to use of a single apparatus, thepresent method can be applied more flexibly than the conventionalmethod; and, the installation cost of the apparatus used in the presentmethod is inexpensive when compared with the apparatus used in theconventional method.

[0066] (2) Because the guide rail is worked using the rolling contact ofthe rotary dies 10, the wear of the dies 10 can be reduced, therebybeing able to extend the life of a tool used.

[0067] (3) As there are obtained, on the rolled surface of the railblank work W, worked continuous fiber tissues which are characteristicof the rolling, the rail blank work W is increased in strength and thematerial of the rail blank work W is enhanced in quality.

[0068] (4) The rail blank work W after heat treatment produces lessstrain. This can reduce the grinding allowance of the rail blank work Win a raceway groove grinding step which can be executed after the heattreatment as the need arises. As a result of this, the grinding time ofthe raceway grooves can be shortened and thus the working cost of theguide rail can be reduced. Also, the warp of the work W caused by thegroove grinding operation can be minimized.

[0069] (5) Use of the rotational contact of the rotary dies 10 makes iteasy to guide lubricant to the working surface of the rail blank work W.

[0070] (6) Since the raceway grooves are rolled after the decarburizedlayer existing on the surface of the rail blank work W is scraped off byan amount of the order of 0.5 mm, there can be obtained sufficientquenched hardness after heat treatment.

[0071] By the way, FIG. 1 shows a case in which only the raceway grooves2 are formed. However, as will be discussed later, in case where a wireholder groove or an oil storage groove is formed in the bottom portionof each of the race grooves 2, by using two projection-shaped dies eachincluding a raceway groove and a wire holder groove or an oil storagegroove, the raceway grooves as well as the wire holder groove or oilstorage groove can be rolled at the same time. According to such two ormore portions simultaneous rolling method, there can be obtained thefollowing advantage: that is, the working operations of a linear guiderail which are conventionally carried out through the separate steps ofdrawing and cutting can be executed by a single working step.

[0072] Now, FIG. 3 shows a second embodiment according to the presentembodiment.

[0073] In the previously described first embodiment, there is used arotary die 10 of an active type including a rotation drive device 11and, on the other hand, the second embodiment is different from thefirst embodiment in that it uses a rotary die 10A of a passive typewhich is free to rotate. That is, the rotary die 10A according to thesecond embodiment is rotated by feeding a rail blank work W which can bepressed in or drawn out in a direction of an arrow mark B by anauxiliary drive device, thereby rolling the raceway grooves 2. In thesecond embodiment, there is obtained an advantage that a rollingapparatus used is simplified in structure by an amount equivalent toomission of the rotation drive device 11 and thus the manufacturing costof a product (a guide rail) can be reduced accordingly. And, theremaining portions of the structure as well as the operation and effectsof the second embodiment are similar to those of the first embodiment.

[0074] Now, FIG. 4 shows a third embodiment according to the presentembodiment.

[0075] In the third embodiment, a pair of rotary dies 10, which aresymmetrically opposed to each other with a rail blank work W betweenthem, are used as a set of rotary dies; and, two or more sets of rotarydies (in FIG. 4, three sets of rotary dies) are disposed in series intwo or more stages (in FIG. 4, in three stages) along the working andfeeding direction of the rail blank work W. While the groove workingdepth of the work W (that is, the distance between the paired dies 10)increases gradually from L₁ in the first stage to L₂ in the next stage,the rail blank work W is worked little by little; and, the rail blankwork W is worked into a final rolling depth L in the final-stage set.That is, the third embodiment is advantageous in that the raceway groove2 can be rolled into a final or finished shape by passing the rail blankwork W through the rotary dies 10 only once. In this working operation,alternatively, the shapes of the working surfaces of the rotary dies 10may be changed in every stage and thus the raceway groove 2 may beworked in the optimum shape in the respective stages.

[0076] By the way, in FIG. 4, there is used a rotary die of an activetype but, of course, it is also possible to use a rotary die of apassive type (see FIG. 3) which does not incorporate therein a rotationdrive device (this can also apply similarly in any of the followingembodiments of the invention).

[0077] And, the remaining portions of the structure as well as theoperation and effects of the third embodiment are similar to those ofthe first embodiment.

[0078] Now, FIG. 5 shows a fourth embodiment according to the invention.

[0079]FIG. 5 is an enlarged view of the outer peripheral surface (grooveworking surface) which is the working portion of a rotary die 15. Theprojection-shaped working portion of the rotary die 15 is formed in atwo-stage shape which is composed of a raceway groove projecting portionT₁ and an oil storage projecting portion T₂ so as to correspond to thegroove shape of the raceway groove 2 of a linear guide rail to berolled. Also, in addition to the projection-shaped working portionhaving two-stage shape composed of the raceway groove projecting portionT₁ and oil storage projecting portion T₂, the rotary die 15 includes abase surface display line projecting portion T₃ for working a basesurface display line 4 and a chamfer working portion T₄ for chamferingthe corner portion We of a rail blank work W.

[0080] By using the rotary die 15 including the plurality of workingportions, in addition to the operation and effects obtained in the firstembodiment, there can be obtained another effect that working can beachieved with extremely high efficiency: that is, rolling of the linearguide rail raceway groove 2, working of an oil storage or wire holdergroove 3 to be formed in the bottom portion of the raceway groove 2,working of the base surface display line 4 and chamfer working of therail corner portion We can be carried out at the same time in a singlestep. Of course, in case where the oil storage projecting portion T₂ ofthe working portion of the rotary die 15, the base surface display lineprojecting portion T₃ thereof and the corner portion chamfer workingportion T₄ thereof are selected properly, as the need arises, any one ofthe oil storage groove 3, reference surface display line 4 and cornerportion chamfer working portion We can also be selectively workedsimultaneously when the raceway grooves 2 are worked.

[0081] Also, by rolling the linear guide rail raceway grooves 2 usingthe rotary dies 10 which are paired with each other with the linearguide rail between them as shown in FIGS. 1 to 4, or by rolling the railblank work W using the rotary die 15 including such two chamfer workingportions T₄ as shown in FIG. 5, there can be obtained the followingadvantage: that is, as shown in FIGS. 6A and 6B, the rail blank work Whas such a cross section that the width-direction two end portions ofthe rail surface (which provide a mounting surface for mounting the railonto a base member) Wc are raised and the width-direction centralportion thereof is dented, thereby being able to enhance the mountingsafety of the thus finished guide rail.

[0082] Specifically, FIG. 6A shows the cross section of a single groovetype which includes a pair of right and left raceway grooves 2 eachhaving an oil storage or wire holder groove 3, and a base surfacedisplay line 4 for the left side surface of a guide rail to be rolled.And, FIG. 6B shows the cross section of a two-groove type which includesnot only a pair of right and left raceway grooves 2 each having an oilstorage or wire holder groove 3 and a base surface display line 4 forthe left side surface of the guide rail to be rolled but also a pair ofright and left ¼ arc-shaped raceway grooves 2A formed on the right andleft corner portions of the upper surface of the guide rail. In thiscase, the linear guide rail is rolled using the rotary die 15 structuredsuch that one (upper surface side) of the two chamfer working portionsT₄ is formed so as to have a ¼ arc-shaped projecting shape. Also, FIG.6C shows a stress state in which a linear guide rail having a dentedrail mounting surface Wc is fixed on the base member by fastening a boltB1. In this case, contact surfaces S1 between the base member and railsurface Wc are only the two width-direction end portions of the linearguide rail excluding the central portion thereof. The sum of the widthsS1 _(w) of two contact surfaces S1 is in the range of approx. 10% to 50%of the whole width of the rail mounting surface Wc. That is, whencompared with contact surfaces S2 provided by a conventional linearguide rail whose rail mounting surface is formed flat shown in FIG. 6D,the present contact surfaces S1 spread out outwardly in the widthdirection of the linear guide rail and, therefore, the linear guide railcan stand firm against lateral loads applied thereto, which can enhancethe mounting strength of the linear guide rail.

[0083] By the way, when using such rotary die 15 having two chamferworking portions T₄ as shown in FIG. 5, in case where the cornerportions We of the rail blank work W prior to rolling are previously cutby an amount equivalent to the portions thereof that would be raisedwhen they are rolled, there can be provided a linear guide rail whoserail lower surface (mounting surface) Wc is flat.

[0084] Now, FIG. 7 shows a fifth embodiment according to the invention.

[0085] In the fifth embodiment, while the distance L between the tworotary dies is being kept constant due to automatic control, the racewaygroove 2 of the linear guide rail is rolled using the rotary dies 10.Specifically, the present embodiment includes an inter-die distance(that is, a distance between the rotary dies 10) measuring machine 16:the inter-die distance L in the vicinity of the working portion of theraceway groove 2 is detected by a sensor 17 and is fed back to a controlunit (not shown), the thus detected and fed-back inter-die distance L iscompared with an inter-die distance set value which has been previouslyinput into the control unit, a difference compensation instruction istransmitted to a moving and pressing mechanism (not shown) to therebycontrol the positions of the two rotary dies 10, 10 in such a mannerthat the inter-die distance L can be kept constant; that is, the racewaygroove 2 of the linear guide rail are rolled using these rotary dies 10in this manner. Therefore, according to the present embodiment, there isobtained an advantage that a linear guide rail with the inter-racewaygroove distance thereof stabilized can be manufactured.

[0086] And, the remaining portions of the structure as well as theoperation and effects of the fifth embodiment are similar to those ofthe first embodiment.

[0087] Now, FIG. 8 shows a sixth embodiment according to the invention.

[0088] In the present embodiment, at the same time when two racewaygrooves 2, 2 are rolled respectively onto the two side surfaces of alinear guide rail using a pair of rotary dies 10, 10, the lower surfaceof the linear guide rail is ground (or cut) using a grinding tool (or acutting tool) 22 while the grinding tool (or cutting tool) 22 is beingpressed against the rail lower surface. Thanks to this, when the tworaceway grooves 2, 2 of the two side rails of the linear guide rail arerolled using the pair of rotary dies 10, 10, the raised portions (seeFIG. 6) produced in the width-direction two end portions of the lowersurface (which provides a rail mounting surface onto a base member) Wcof the linear guide rail can be removed to thereby form the railmounting surface Wc into a flat surface. This can enhance thelongitudinal-direction parallelism of the rail raceway grooves 2, 2 withrespect to the lower surface of the linear guide rail without increasingthe number of steps of working the rail raceway grooves. In the abovedescription of FIG. 6, as the advantage of the raised portions producedby the rolling of the rail raceway grooves 2, 2, there was pointed out afact that a linear guide rail including a mounting surface having adented width-direction central portion can be enhanced in stability whenit is mounted onto its base member and the strength of such linear guiderail can be thereby increased. On the other hand, the raised portionsprovide an indefinite factor to the relative dimension between the railraceway grooves 2, 2 and the rail mounting surface. In view of this, inthe use that requires high dimensional accuracy between the rail racewaygrooves 2, 2 and rail mounting surface, it is preferred that the railmounting surface may be ground (or cut) into a flat shape at the sametime when the rail raceway grooves 2, 2 are rolled.

[0089] For reference, to secure the parallelism of the rail racewaygrooves simply through rolling, it is necessary that the guide rollersof a positioning and supporting device 13 respectively disposed on theupper and lower surfaces of the linear guide rail are pressed againstthe linear guide rail to thereby crash the raised portions of the rail.In fact, however, it is almost impossible to roll the four surfaces ofthe linear guide rail at the same time, because the guide rollersinterfere with each other.

[0090] Now, FIG. 9 shows a seventh embodiment according to theinvention.

[0091] In the present embodiment, at the same time when two racewaygrooves 2, 2 are rolled respectively onto the two side surfaces of alinear guide rail using a pair of rotary dies 10, 10, the upper andlower surfaces of the linear guide rail are ground (or cut) usinggrinding tools (or cutting tools) 23, 24 while the grinding tool (orcutting tool) 23, 24 are being pressed against the rail upper and lowersurfaces respectively. That is, in the present embodiment, the tworaceway grooves 2, 2 of the two side surfaces of the linear guide railcan be rolled using the pair of rotary dies 10, 10. Simultaneously withsuch rolling of the raceway grooves 2, 2, not only, using the grindingtool 23, the raised portions (see FIG. 6) produced in thewidth-direction two end portions of the upper surface Wa of the linearguide rail are removed and the rail upper surface Wa is formed into aflat surface while chamfering the width-direction two end portions ofthe upper surface Wa, but also, using the grinding tool 24, the raisedportions (see FIG. 6) produced in the width-direction two end portionsof the lower surface (which provides a rail mounting surface onto a basemember) Wc of the linear guide rail are removed and the rail lowersurface Wc is formed into a flat surface while chamfering thewidth-direction two end portions of the rail lower surface Wc.

[0092] Thus, according to the seventh embodiment, the parallelism of therail raceway grooves 2, 2 in the longitudinal direction thereof withrespect to the lower surface of the linear guide rail can be enhancedwithout increasing the number of steps of working the rail racewaygrooves 2, 2.

[0093] Now, FIG. 10 shows an eighth embodiment according to theinvention.

[0094] The eighth embodiment is a modified version of the fifthembodiment shown in FIG. 7. The eighth embodiment includes aninter-groove distance (that is, a distance between two raceway grooves)measuring machine 18 instead of the above-mentioned inter-die distance(that is, a distance between two rotary dies) measuring machine 16: thatis, a distance 1 between the two raceway grooves 2, 2 just after theyare rolled using the two rotary dies 10, 10 is measured by bringing asensor 19 into direct contact with the bottom portions of the racewaygrooves 2. In accordance with the measured result, the positions of therotary dies 10, 10 are fed back and controlled by a moving and pressingmechanism (not shown) in such a manner that the inter-groove distance 1can provide a desired distance. Thanks to this, according to the presentembodiment, similarly to the previously described fifth embodiment, itis possible to roll a linear guide rail in which the inter-groovedistance 1 is stabilized.

[0095] And, the remaining portions of the structure as well as theoperation and effects of the eighth embodiment are similar to those ofthe first embodiment.

[0096] Now, FIG. 11 shows a ninth embodiment according to the invention.

[0097] In all of the previously described embodiments, the axis of alinear guide rail is linear. On the other hand, according to the presentembodiment, there is provided a method for working a curved rail.

[0098] In the present embodiment, three rolling rotary dies 10 are usedas a set: specifically, two of them are disposed on one side of a railblank work W, whereas the remaining one is disposed at the middleposition of the two dies on the other side of the rail blank work W.That is, raceway grooves 2, 2 are respectively rolled on the two sidesof the rail blank work W using a set of (three) rotary dies, whereby alinear guide rail having a curvature can be worked simultaneously whenthe raceway grooves 2 are rolled. The curvature of the guide rail W canbe adjusted by adjusting a die pressing force as well as arail-axis-direction distance H between the two rotary dies 10.

[0099] Now, FIG. 12 shows a tenth embodiment according to the invention.

[0100] In the present embodiment, using three rotary dies 10, racewaygrooves (spline grooves) 2 are rolled in the three equal peripheralportions of a rail blank work W having a circular section of a ballspline shaft which is one kind of a linear guide rail. In theillustrated embodiment, three rotary dies 10 each of an active type tobe driven or rotated by a motor 11 through a belt 12 are disposed atequally spaced positions along the periphery of the rail blank work W,and the raceway grooves 2 are rolled on the rail blank work W usingthese three rotary dies 10. However, the number of rotary dies is notalways limited to three.

[0101] And, the remaining portions of the structure as well as theoperation and effects of the tenth embodiment are similar-to those ofthe first embodiment.

[0102] Now, FIGS. 13A and 13B show an eleventh embodiment according tothe invention.

[0103] In the present embodiment, raceway grooves are rolled on an oddnumber of surfaces of a rail blank work W having a square section of across roller guide which is a kind of, for example, a circular-typelinear guide rail.

[0104] Specifically, FIG. 13A shows a case in which a raceway groove 2is worked on the only one surface of the rail blank work W; and, in thiscase, there is disposed a groove working rotary die 10 and, on theopposing side of the groove working rotary die 10, there is disposed aload receiving rotary die 20. In the load receiving rotary die 20, thecircumferential surface thereof is not formed in such a projecting shapeas in the groove working rotary die 10 but is formed simply cylindrical:that is, the load receiving rotary die 20 may only be able to receivethe load of the groove working rotary die 10 which is disposed on theopposing side of the load receiving rotary die 20, while the loadreceiving rotary die 20 can be driven or rotated by a motor 11 through abelt 12.

[0105] Also, FIG. 13B shows a case in which raceway grooves 2 are rolledon the three surfaces of the rail blank work W. In this case,perpendicularly to the above-mentioned groove working rotary die 10 forrolling a raceway groove onto one surface of the rail blank work W,there are further disposed a pair of groove working rotary dies 10, 10in such a manner that these two rotary dies 10, 10 are opposed to eachother with the remaining surfaces of the rail blank work W between them;and, the raceway grooves 2 are respectively rolled on the three surfacesof the rail blank work W.

[0106] Thus, according to the raceway groove working method shown inFIGS. 13A and 13B, there is obtained an advantage that a linear guiderail having raceway grooves on an odd number of surfaces of the railblank work W or having an odd number of raceway grooves thereon can berolled accurately and easily.

[0107] And, the remaining portions of the structure as well as theoperation and effects of the eleventh embodiment are similar to those ofthe first embodiment.

[0108] While only certain embodiments of the invention have beenspecifically described herein, it will apparent that numerousmodifications may be made thereto without departing from the spirit andscope of the inveniton.

[0109] As has been described heretofore, according to the invention,since a rolling technique is applied to working of one or more racewaygrooves of a linear guide rail to thereby form raceway grooves havinggood accuracy only by a single working step, when compared with aconventional method requiring a plurality of steps of drawing, cuttingand grinding a linear guide rail, the working time and cost of theraceway grooves and thus the linear guide rail can be reduced.

[0110] Also, even in case where the thus worked raceway grooves areground in order to secure extremely high accuracy as the need arises,the grinding allowance can be minimized, which makes it possible toshorten the grinding time of the linear guide rail, reduce the workingcost thereof, and enhance the working accuracy thereof.

What is claimed is:
 1. A linear guide rail, comprising: at least oneraceway groove along which rolling bodies roll, said raceway groovebeing subjected to rolling work.
 2. The linear guide rail according toclaim 1, wherein the surface roughness of said raceway groove in thelongitudinal direction thereof is in the range of 0.05-0.2 Ra.
 3. Thelinear guide rail according to claim 1, further comprising: a lowersurface formed in such a dented shape that the width-direction two endportions thereof are projected slightly up from the width-directioncentral portion thereof.
 4. The linear guide rail according to claim 1,wherein a surface of said linear guide rail to be rolled is subjected toremoval of a decarburized layer.
 5. A method for working a linear guiderail having at least one raceway groove along which rolling bodies roll,comprising the steps of: preparing at least one of rotary dies includinga projection-shaped working portion matched in shape to said racewaygroove; and rolling said raceway groove on a rail blank work of saidlinear guide rail by said rotary dies.
 6. The method according to claim5, further comprising the step of: grinding a lower surface of said railblank work at the same time of the rolling of said raceway groove. 7.The method according to claim 5, further comprising the step of: cuttinga lower surface of said rail blank work at the same time of the rollingof said raceway groove.
 8. The method according to claim 5, furthercomprising the step of: performing at least one of chamfering of acorner portion of said linear guide rail, formation of an oil storagegroove in said raceway groove, and formation of a base surface displayline, by using said same rotary dies at the same time of the rolling ofsaid raceway groove.
 9. The method according to claim 5, wherein, byrolling said raceway groove using said rotary dies, the width-directiontwo end portions of a mounting surface of said linear guide rail areprojected slightly up from the width-direction central portion thereof.10. The method according to claim 5, further comprising the steps of:measuring a distance between working positions of said rotary dies or adistance between portions adjacent to said working positions by asensor; and controlling a distance between said rotary dies so as to beconstant, to thereby maintain a distance between said raceway groovesstably.
 11. The method according to claim 5, further comprising thesteps of: measuring positions of said raceway grooves by a sensor justafter said raceway grooves are rolled by said rotary dies, to therebydetect the positions of said raceway grooves; and controlling thepositions of said rotary dies in accordance with said detected values,to thereby maintain said distance between said raceway grooves stably.12. The method according to claim 5, wherein, in said preparing step,two rotary dies are disposed spaced from each other on one side of saidlinear guide rail to be rolled with said two opposing raceway grooves,and a rotary die is disposed on the other side of said linear guide railso as to be asymmetric with respect to said two rotary dies, and whereinsaid linear guide rail is bent simultaneously while rolling said racewaygrooves by said rotary dies, to thereby form a linear guide rail havinga curvature.
 13. The method according to claim 5, further comprising thesteps of: heat treating said linear guide rail after said rolling step;and grinding said raceway groove, to thereby finish said raceway groovewith high accuracy.